This application claims benefit of Japanese Patent Application No. 2000-227691 filed on Jul. 27, 2000, the contents of which are incorporated by the reference.
The present invention relates to a disk system with contents play-back restriction mechanism for restricting the contents play-back by deleting contents read-out data stored in a memory after lapse of a predetermined time.
As a pertaining prior art, a method of storing contents on a DVD-ROM or the like is well known. In this method, ciphered contents and contents deciphering key are stored on a medium, and a player deciphers the contents by reading out the contents deciphering key stored on the medium and then plays back the contents.
As another pertaining art, a method is well known, in which, while contents are stored in a DVD-ROM or the like, a player obtains contents deciphering key from a center by a telephone call.
As a further pertaining prior art, Japanese Patent Laid-Open No. 11-175406 discloses a method, in which a battery and a connection detector are provided in an auxiliary memory such as to delete data upon illegal data take-out detection.
In the first-mentioned prior art method, the data written on the medium is not changed with the lapse of time and can thus be viewed forever. Therefore, a problem is posed that when renting contents with a DVD-ROM for a fixed period of time, it becomes necessary to return the DVD-ROM to the shop after the lapse of the fixed time.
In the second-mentioned prior art, every time when playing back contents, the player should obtain the contents key by a telephone call, which is very cumbersome.
In the third-mentioned prior art, although it is possible to realize protection of data from illegal take-out thereof, it is impossible to realize a function as in the case of renting contents, i.e., a function of permitting effective read-out of contents until the lapse of a certain period of time but not permitting subsequent contents play-back.